Image forming apparatus

Abstract

An image forming apparatus may include: a heating unit including a heating member that is heated by a heat source and a backup member that forms a nip portion; a feeding unit; and a control unit configured to control the heat source and the feeding unit, wherein the control unit controls the feeding unit such that each of a plurality of recording sheets is fed to the nip portion, wherein some of the plurality of the recording sheets are sequentially conveyed at a second interval to each other, wherein a first recording sheet of the some of the plurality of the recording sheets is fed to have a first interval with respect to a previously conveyed recording sheet, and wherein the control unit increases the output of the heat source on a timing when a front end of the first recording sheet reaches a periphery of the nip portion.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 a heating unit including:
 a heating member; 
 a heat source configured to heat the heating member; and 
 a backup member facing the heating member, a nip portion being defined between the heating member and the backup member; 
 
 a feeding unit configured to feed a recording sheet toward the nip portion; and 
 a control unit configured to:
 control the feeding unit such that each of a plurality of recording sheets is fed to the nip portion at one of a first interval and a second interval smaller than the first interval, two of the plurality of the recording sheets being sequentially conveyed at the second interval to each other, a first recording sheet of the two of the plurality of the recording sheets being fed to have the first interval with respect to a previously conveyed recording sheet, and 
 increase an output of the heat source when a front end of the first recording sheet reaches a periphery of the nip portion, 
 wherein the control unit alternately performs a conveyance at the first interval and a conveyance at the second interval. 
 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein the control unit is configured to increase the output of the heat source immediately before the front end of the first sheet reaches the nip portion. 
     
     
       3. The image forming apparatus according to  claim 1 , wherein the control unit is configured to decrease the output of the heat source on a timing when a rear end of the first recording sheet reaches the periphery of the nip portion. 
     
     
       4. The image forming apparatus according to  claim 1 , wherein the control unit is configured to decrease the output of the heat source when a rear end of a last recording sheet of the two of the plurality of recording sheets sequentially conveyed at the second interval reaches the periphery of the nip portion. 
     
     
       5. The image forming apparatus according to  claim 4 , wherein the control unit is configured to decrease the output of the heat source after the rear end of the last recording sheet of the two of the plurality of recording sheets sequentially conveyed at the second interval leaves the periphery of the nip portion. 
     
     
       6. The image forming apparatus according to  claim 1 , wherein when performing duplex printing on the recording sheets, the control unit is configured to alternately perform the conveyance at the first interval and the conveyance at the second interval. 
     
     
       7. The image forming apparatus according to  claim 1 , further comprising:
 a temperature detecting member configured to detect the temperature of the heating unit, 
 wherein, in a case where a current value of a detected temperature detected by the temperature detecting member is lower than a target temperature, the control unit is configured to increase the output of the heat source, and 
 wherein, in a case where the current value is higher than the target temperature, the control unit is configured to decrease the output of the heat source. 
 
     
     
       8. The image forming apparatus according to  claim 7 , wherein the control unit is configured to change the target temperature to change the output of the heat source. 
     
     
       9. The image forming apparatus according to  claim 8 , wherein, in a case of lowering the target temperature having greatly changed from an initial value to the initial value, the control unit is configured to gradually lower the target temperature to the initial value.